A polymerizable liquid crystal compound having a liquid crystal phase yields an optical anisotropic film having a function such as optical compensation by polymerization because alignment of polymerizable liquid crystal molecules is immobilized by poylmerization. Various polymerizable liquid crystal compounds have been developed in order to utilize such a function of the optical anisotropic film, but a sufficient function is not satisfied by one polymerizable liquid crystal compound in some cases. Therefore, an attempt has been made in which a composition is prepared using several polymerizable liquid crystal compounds to allow polymerization of the composition.
In an alignment state of a liquid crystal material, showing a state of alignment such as homogeneous alignment (horizontal alignment), tilt alignment (tilted alignment), homeotropic alignment (vertical alignment) or twist alignment (twisted alignment) is occasionally described simply as “having homogeneous alignment,” “having tilt alignment,” “having homeotropic alignment,” “having twist alignment” or the like.
An optical anisotropic film having the tilt alignment can be applied to, for example, a viewing angle compensating plate in a twisted nematic (TN)) mode (see Patent literature No. 1).
In the applications described above, the liquid crystal material may be occasionally laminated on a support substrate such as a glass substrate or a plastic substrate. Examples of the material used as the plastic substrate include a polymer such as triacetyl cellulose (TAC), polycarbonate, polyethylene terephthalate (PET) and cycloolefin resins.
Specific examples of the polymerizable liquid crystal composition in which the liquid crystal material shows the tilt alignment include a polymerizable liquid crystal composition containing an acrylate derivative having a 9,9-dialkylfluorene skeleton as a main component (see Patent literature No. 2), and a polymerizable liquid crystal composition formed of a monofunctional compound having a bond in a polymerizable moiety in a center of a mesogen skeleton and a polymerizable compound having a bisphenol skeleton (see Patent literature No. 3). Moreover, as a method for controlling tilt alignment of a liquid crystal material, a proposal has been made for a method for manufacturing an optical anisotropic film in which the number of carbon atoms in a spacer group of a polymerizable liquid crystal compound is controlled (see Patent literature No. 4).
However, the polymerizable liquid crystal composition described above is difficult to develop a moderate tilt angle, or when a polymerizable liquid crystal compound in which the number of carbon atoms of the spacer group is changed is applied to the composition for the purpose of controlling the tilt alignment, an amount of intermediate raw material increases in a manufacturing step, thereby increasing manufacturing cost in some cases. Therefore, a desire has been expressed for a polymerizable liquid crystal composition having structure facilitating development of the tilt angle of the liquid crystal material in the tilt alignment and allowing manufacture at low cost.